How would one repair a non-power locking door of a 1990 Toyota Pickup that's not opening from the inside?

Remove the door panel, check the fastener to the inside handle to make sure it is connected if it is ok then on to checking to see if the door opening handle rod is connected to the latch, most times the plastic or metal retaining clip will break or fall off. If both of these rods are connected firmly, then it may be that the springs inside of your actual door latch are At Fault, thus having to replace the latch itself.